Soil organic carbon is one of the soil quality parameters. Soil organic carbon and total nitrogen play an important role in soil physicochemical fertility. The purpose of this paper was to observe the dynamics of organic matter and nitrogen content in paddy soil in Java. Data is obtained from the collection of various research results since 1990, then to analyze the correlation between the chemical properties of the soil. Out of 860 data in five provinces in Java showed a strong correlation between soil organic carbon content and total nitrogen. More than 77% of the paddy soil in Java have low soil organic carbon content as well as more than 80% have a low total nitrogen content. The positive correlation between soil organic carbon content and total nitrogen is quite strong. Correlation coefficients were 0.842 in Banten, 0.900 in West Java 0.895 in Central Java, 0.798 in East Java and 0.898 in Yogyakarta. From this linear regression can be seen that the higher the soil organic carbon content, the ability of the soil to retain nitrogen will also be higher. We can manage soil fertility, especially the nitrogen availability in the soil by maintaining the soil organic matter content.

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Semen PCC, agregat halus, agregat kasar, air, dan styrofoam dengan perbandingan variasi yang berbeda-beda yakni 10% dan 30% terhadap volume beton serta penambahan abu sekam padi dengan variasi 5%, 10% dan 15% terhadap volume semen. Dari hasilpercobaankuat tekan beton kandungan styrofoam 10% dengan variasi abu sekam 15% yaitu rata rata sebesar 90,79 kg/cm2. Mengalami peningkatan sebesar 3,34%. Dari hasil percobaan uat tekan beton kandungan styrofoam 30% dengan variasi abu sekam 15% yaitu sebesar 67,35 kg/cm2. Mengalami peningkatan sebesar 3,9%. Kuat lentur beton kandungan styrofoam 10% dengan variasi abu sekam 15% yaitu sebesar 3,21MPa meningkat sebesar 6%. Kuat lentur beton kandungan styrofoam 30% dengan variasi abu sekam 15% yaitu sebesar 2,79MPa meningkat sebesar 7%. Beton dengan kandungan styrofoam 30% mempunyai berat per isi rata-rata sebesar1866,67 kg/m3. Artinya beton tersebut bisa dikategorikan sebagai beton ringan karena berat jenisnya kurang dari 1900 kg/m3 seperti yang dipersyaratkan SNI 03 -1729 -2002. Hasil penelitian ini diharapkan bermanfaat memberi informasi mengenai perilaku mekanik beton ringan dengan tambahan styrofoam dan abu sekam padi. Dapat dijadikan bahan referensi mengenai persentase styrofoam dengan tambahan abu sekam padi yang baik digunakan dalam campuran beton. Kata kunci: styrofoam, abu sekam padi, beton ringan.

One of the problems in the synthesis of Hydroxyl Terminated Polybutadiene for propellant binders is the level of vinyl is high (up to 30%), while the desired product is 20%. Vinyl bond can be reduced if the chain can be broken with the addition of a hydroxyl group. The research objective is to reduce the amount of vinyl structure in HTPB with the addition of double bonds in the vinyl by applying Sayef Sain reaction. HTPB is reacted with concentrated hydrogen peroxide with the Sain Sayef catalyst in the 1 liter autoclave reactor with ethanol for 1-3 hours at 100° C. After being purified by extraction in hot water and drying, it is analyzed by an infrared spectrometer. The result shows that there is a change in the concentrations of vinyl within the polymers produced by observing the absorption of vinyl groups at a wavelength of 690cm -1 . Optimal results obtained with vinyl content of 20% with a temperature of 100° C for 90 minutes. In general, the quality of HTPB can be increased by reducing the levels of vinyl which allowing the HTPB composition to have a vinyl content reduced to 19%.